| cbind {base} | R Documentation |
Combine R Objects by Rows or Columns
Description
Take a sequence of vector, matrix or data frames arguments and combine by columns or rows, respectively. There may be methods for other R classes.
Usage
cbind(...)
rbind(...)
Details
The functions cbind and rbind are generic, with methods
for data frames. The data frame method will be used if an
argument is a data frame and the rest are vectors or matrices. There
can be other methods, for example cbind.ts
in package ts.
If there are several matrix arguments, they must all have the same
number of columns (or rows) and this will be the number of columns (or
rows) of the result. If all the arguments are vectors, the number of
columns (rows) in the result is equal to the length of the longest
vector. Values in shorter arguments are recycled to achieve this
length (with a warning when they are recycled only
fractionally).
When the arguments consist of a mix of matrices and vectors the number of columns (rows) of the result is determined by the number of columns (rows) of the matrix arguments. Any vectors have their values recycled or subsetted to achieve this length.
Note
The method dispatching is not done via
UseMethod(..), but by C-internal dispatching.
Therefore, there's no need for, e.g., rbind.default.
The dispatch algorithm is described in the source file (‘.../src/main/bind.c’) as
For each argument we get the list of possible class memberships from the class attribute.
We inspect each class in turn to see if there is an an applicable method.
If we find an applicable method we make sure that it is identical to any method determined for prior arguments. If it is identical, we proceed, otherwise we immediately drop through to the default code.
If you want to combine other objects with data frames, it may be necessary to coerce them to data frames first.
See Also
c to combine vectors (and lists) as vectors,
data.frame to combine vectors and matrices as a data frame.
Examples
cbind(1, 1:7) # the '1' (= shorter vector) is recycled
cbind(1:7, diag(3))# vector is subset -> warning
cbind(0, rbind(1, 1:3))
cbind(0, matrix(1, nrow=0, ncol=4))#> Warning (making sense)
dim(cbind(0, matrix(1, nrow=2, ncol=0)))#-> 2 x 1